Determine the Values for Which a Rational Expression is Undefined

Timestamps for Examples -
Intro – 0:00
Example 1 – 3:09
Example 2 – 10:11
Example 3 – 11:56
Example 4 – 14:56
Example 5 – 16:28
Example 6 – 17:55
Example 7 – 20:02
Example 8 – 21:23
Example 9 – 22:30
Example 10 – 24:26
Example 11 – 25:11
Example 12 – 26:17